1. Field of the Invention
This invention relates generally to transmissions for pedal powered vehicles such as bicycles and tricycles and more particularly to bicycle drive mechanisms of the chainless planetary type.
2. Description of the Prior Art
The most common multiple speed bicycle uses a chain and derailleur system. The chain requires periodic cleaning and oiling for efficient operation and to prevent premature chain failure and must be removed from the rear sprocket to change the tire. Chain maintenance is particularly troublesome if the bicycle is ridden extensively on dirt roads and trails.
The transmission described in U.S. Pat. No. 2,505,464 by Debuit is a chainless type, located on the axis of the front wheel concentric with the pedal drive shaft, but Debuit's transmission is not planetary, and is mounted alongside the wheel hub. Moreover, the pedal torque is carried through single gear teeth, thus requring heavy gears to prevent early fatigue failure of the gear teeth.